Multistep thermodesorption coupled with molecular analyses as a quick, easy and environmentally friendly way to measure PAH availability in contaminated soils

Whether it is for risk assessment or for remediation purpose, contaminant availability in polluted soils is a key parameter to determine. Two methods were recently standardized for the estimation of the environmental available fraction of non-polar organics but, in some cases, their application on real historically contaminated soils does not provide satisfactory results. The present study aimed at proposing an alternative method for the estimation of PAH availability in soils, based on analytical thermal desorption and molecular analyses with the hypothesis that the binding strength between PAH and the solid matrix is linked to the desorption temperature. This hypothesis was validated by comparing the thermodesorption molecular distribution of different contaminated soils and of their respective extractable organic matter. Then, comparing the thermodesorption profiles of each studied PAH to the efficiency of biological and chemical remediation treatments through principal component analysis allowed obtaining the desorption temperature corresponding to PAH fractions available towards both treatments. This method was proven to effectively estimate the PAH fraction available towards biological (microbial incubation) and chemical (KMnO4 oxidation) treatments and present multiple advantages such as being fast, easy to execute and solvent free. [Display omitted] •PAH desorption temperature is linked to its binding strength with the matrix.•Thermodesorption-GC-MS/FID coupling is proposed to determine PAH availabilities.•Desorption temperature corresponding to the available fraction is defined using PCA.•Comparison of degradation efficiency and availability estimation shows a good match.•Better results obtained with Td availability method than with the standardized ones.